1. Field
The field of the invention is apparatus for preparing and grooming snow slopes for skiing, and more particularly devices for finally smoothing the snow after tilling or other initial preparation.
2. State of the Art
Various snow grooming devices have been used to smooth and recondition the snow of ski slopes. These are generally drawn over the snow behind a tracked vehicle, which may carry a forward blade for preliminary leveling of the snow. Harrows, discs, rollers, snow compacting bars and tillers are examples of these devices. One of the most widely used are the snow tillers, which are powered to aggressively break up and cut snow which is packed from extended use or weather conditions. While it is not "powder", tilled snow is in the form of relatively small aggregated pieces, and when lightly but firmly packed provides easy, enjoyable skiing. Tillers commonly in use have blades on rotating cutter bars covered by an apron with its trailing edge positioned bearing on the snow surface to smooth and compact the cut and chopped snow. Initially, the metallic edge of the skirt was relied upon and no further conditioning of the snow was provided. Sometimes this trailing edge was provided in saw tooth form or a saw tooth edge member was attached to the trailing edge. Later, a flexible, saw tooth member was attached to this trailing edge, such as member 33 disclosed in U.S. Pat. No. 4,359,831. Positioned to bear forcibly upon the snow, the trailing edge comb structure 33 further crushed and reduced snow lumps and the like, considerably improving the final surface for skiing. Subsequently more elaborate devices were employed in the skirt trailing edge area. Instead of the short saw tooth member, devices of much greater length proved advantageous. These longer members bore forcefully downward upon the snow over an increased area of contact, and more effectively powdered the snow. The saw tooth edge comb teeth evolved into parallel ridges, elongate in the direction of travel, bearing generally horizontally upon the snow. Powdering was improved by the ridges. Later, a second and then a third row were used, the individual ridges aligned from row to row. The ridges of each row were of equal length and were positioned side by side. Generally, a substantial space was provided between succeeding rows allowing increased flexibility for more extended snow contact. Later, as disclosed in U.S. Pat. No. 4,897,941, elongate teeth of the rows were provided in alternate short and long lengths, with the long teeth aligned with short teeth of following rows, to horizontally as well as vertically powder and work the surface of the snow. Still, even with this approach, the final snow surface was produced in the form of parallel corrugations. Also disclosed in the aforesaid patent, was a comb design incorporating at its trailing edge a row of elongate teeth arranged in parallel orientation to each other but directed angularly to the direction of travel. This produced a snow surface of improved powdered condition without the corrugations which have the tendency in some weather conditions to become hardened so as to undesirably seize the edges of skis. However, this approach was perhaps unnecessarily complex and costly. Clearly, although the prior art final grooming devices had been improved considerably, further improvement was needed for more economical devices producing safer more enjoyable skiing.